PHILADELPHIA -- Second baseman Chase Utley left Wednesday night's 3-2 victory against Atlanta for precautionary reasons after a possible concussion.

The Phillies will wait a couple of days before giving Utley an ImPACT concussion test. They will compare those results with a baseline test given during Spring Training to determine when Utley can return, general manager Ruben Amaro Jr. said.

"We think it's very, very mild, but we're going to be cautious with him, obviously," Amaro said. "You don't want to mess with the head."

Team physician Dr. Michael Ciccotti, head athletic trainer Scott Sheridan and a concussion specialist have decided not to have Utley fly to Milwaukee, where the team opens a four-game series against the Brewers on Thursday. Utley will instead begin consulting with a doctor.

"As I told Chase in there, we're not going to mess with the heart, and we're not going to mess with the head," Amaro said. "When you get a 90-plus mile an hour fastball off your melon, you have to be cautious about it regardless what kind of gear you're wearing."

Utley was hit on the back of the batting helmet by left-handed reliever Eric O'Flaherty in the sixth inning without attempting to get out of the way. Manager Charlie Manuel said after the game that Utley did not see the pitch coming toward his head.

Utley remained in the game and started to get a headache while playing the field in the seventh, Manuel said. Ben Francisco batted for Utley in the eighth, then Pete Orr replaced him at second base.

Amaro said the Phillies will likely activate shortstop Jimmy Rollins from the disabled list, but they will only play him in an emergency situation. Rollins is still recovering from a strained right groin.

Nate Mink is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.